In various fields of the technique, liquids have entrained therein solid particles. In order to remove these solid particles from the liquids, they are passed through filters. During such filtering processes, however, the solids accummulate on the filter material and in its pores. This reduces the efficiency of such filters more and more so that eventually the operation of the filter has to be shut down either to remove the layer of solids from the filter material or to replace the entire filter material by a fresh one. It would be desirable to have a continuously operable filter system and filtering process.